The present invention relates to hermetic terminal assemblies and more particularly to a fused hermetic terminal assembly including an improved fuse, and also to an improved pin guard and lead wire end connection securing device associated with the hermetic terminal assembly.
It is known in the art of hermetic terminal assemblies to employ a current carrying electrically connected terminal pin, which pin incorporates a reduced fuse-like area generally located on the inner segment of the pin on the inner dish side face of a cup-shaped body of the terminal assembly. The cup-shaped body, in turn, is mounted in sealed relation on a housing wall with the inner segment of the pin being confined therein. It also is known in the art to include a stop flange between the extremity of the inner segment of the pin and such fuse-like area within the cup-shaped body in the event such fuse-like area should melt because of abnormally excessive current conditions. In this regard, attention is directed to U.S. Pat. No. 4,584,433 issued to Benjamin Bowsky et al. on Apr. 22, 1986; U.S. Pat. No. 4,609,774 issued to David M. LeMieux et al. on Sept. 2, 1986; and, to U.S. Pat. No. 4,739,551, issued to Benjamin Bowsky et al. on Apr. 26, 1988, each of which patents broadly teaches the utilization of a fuse-like area incorporated as part of an inner segment, of a pin and a flange member associated therewith, the latter patent further teaching the roll-forming of such fuse-like area. In addition, attention is directed to U.S. Pat. No. 4,461,925, issued to Benjamin Bowsky et al. on July 24, 1984, which patent teaches a terminal pin having a stop flange associated therewith and which further includes a reduced area positioned immediately adjacent the outside area of the seal and cup-shaped body with no mention being made in this patent of a coating for such reduced area or of a pin guard and lead wire end connection securing device. Attention also is directed to U.S. Pat. No. 4,252,394, issued to Austin S. Miller on Feb. 24, 1981, which teaches a terminal pin having two sections of different cross-sectional area with the larger and smaller sections joining within the sealing area inside the cup-shaped body. Finally, attention is directed to U.S. Pat No. 3,160,460, issued to A. Wyzenbeek on Dec. 8, 1964 and U.S. Pat. No. 4,296,275, issued to B. Bowsky on Oct. 20, 1981, each of which broadly teaches the use of a silicone rubber insulator on the outer face of the cup-shaped body of a terminal assembly to insulate the body, with the insulator including spaced protuberances to insulate a portion of the terminal pins extending from the outer face of the cup-shaped body, U.S. Pat. No. 3,160,460 also broadly suggesting an outer pin segment guard in the form of a terminal block.
In accordance with the present invention, it is recognized that, as suggested in the earlier Bowsky et al. U.S. Pat. No. 4,461,925, it is desirable to locate the fuse-like area adjacent the outer face of the cup-shaped body of a terminal assembly to keep abnormally excessive currents from reaching and melting the glass which serves to form a seal between the pin and cup-shaped body of the terminal assembly. It further is recognized by the present invention that, if the glass seal between pin and cup-shaped body reaches an elevated temperature above that anticipated for the fuse-like area to reach softened or molten state, it offers a path for a trickle current and eventually this could allow the terminal assembly to vent to ambient. Such a desirable relative location of the fuse-like area of the pin of the terminal assembly outside the cup-shaped body not only has not been utilized in the more recent past, but, as is reflected in the structure disclosed in the aforementioned later issued patents to Bowsky et al., namely U.S. Pat. Nos. 4,584,433 and 4,739,551, the fuse-like area incorporated in the pin has been located on the inner segment of the terminal assembly pin, usually between a comparatively costly to manufacture stop-flange and the extremity of the inner segment of the pin, notwithstanding such glass melting problems. The present invention, recognizing the desirability of the location for the fuse-like area on the outer face or outside of the terminal assembly and further recognizing the reason for avoiding such selection in the recent past, provides a novel structure which obviates these now recognized problems, the present invention including the utilization of a novel, comparatively light and inexpensive means for covering the exposed outer segment of a pin in which the outer fuse-like area has melted, such means functioning like a terminal block and further serving as a pin restraint during normal operations to avoid usage of the comparatively costly and more difficult to assemble stop-flange on the inner segment of the terminal pin and the cumbersome and comparatively difficult to assemble outer pin segment guard assemblies mounted on outer housing walls in past arrangements. In addition, the present invention provides a novel current resistive pin guard and lead wire end connection securing device for the outer segment of the pin means and wire connections of a terminal assembly which, in the event of fuse melt, serves to hold the lead wire ends in position to help prevent free floating of electrically alive wires. Further, the present invention not only provides a novel, comparatively inexpensive to manufacture and assemble current resistive integral pin guard and lead wire end connection securing device for the external segments of otherwise exposed outer pin segments of a terminal assembly, but also provides a novel means for readily mounting such integral pin guard and lead wire end connection securing device allowing the same to be bonded or fastened firmly in place to restrict ready access thereto, thus helping to minimize some of the safety problems which can arise through improper repair attempts.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.